package ldh.common.spring.security.cryptogram;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import java.security.SecureRandom;
import java.util.Base64;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * Created by ldh123 on 2018/10/13.
 */
public class AesUtil {

    private static final String KEY_ALGORITHM = "AES";
    private static final String DEFAULT_CIPHER_ALGORITHM = "AES/ECB/PKCS5Padding";//默认的加密算法

    /**
     * AES 加密操作
     *
     * @param content 待加密内容
     * @param password 加密密码
     * @return 返回Base64转码后的加密数据
     */
    public static String encrypt(String content, String password) {
        try {
            Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);// 创建密码器
            byte[] byteContent = content.getBytes("utf-8");
            cipher.init(Cipher.ENCRYPT_MODE, getSecretKey(password));// 初始化为加密模式的密码器
            byte[] result = cipher.doFinal(byteContent);// 加密
            return Base64.getEncoder().encodeToString(result);//通过Base64转码返回
        } catch (Exception ex) {
            Logger.getLogger(AesUtil.class.getName()).log(Level.SEVERE, null, ex);
            throw new RuntimeException("aes encrypt error!");
        }
    }

    /**
     * AES 解密操作
     *
     * @param content
     * @param password
     * @return
     */
    public static String decrypt(String content, String password) {
        try {
            //实例化
            Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);
            //使用密钥初始化，设置为解密模式
            cipher.init(Cipher.DECRYPT_MODE, getSecretKey(password));
            //执行操作
            byte[] result = cipher.doFinal(Base64.getDecoder().decode(content));
            return new String(result, "utf-8");
        } catch (Exception ex) {
            Logger.getLogger(AesUtil.class.getName()).log(Level.SEVERE, null, ex);
            throw new RuntimeException("aes decrypt error!");
        }
    }

    /**
     * 生成加密秘钥
     *
     * @return
     */
    private static SecretKeySpec getSecretKey(final String password) {
        //返回生成指定算法密钥生成器的 KeyGenerator 对象
        KeyGenerator kg = null;
        try {
            kg = KeyGenerator.getInstance(KEY_ALGORITHM);
            //AES 要求密钥长度为 256
            kg.init(128, new SecureRandom(password.getBytes("utf-8")));
            //生成一个密钥
            SecretKey secretKey = kg.generateKey();
            return new SecretKeySpec(secretKey.getEncoded(), KEY_ALGORITHM);// 转换为AES专用密钥
        } catch (Exception ex) {
            Logger.getLogger(AesUtil.class.getName()).log(Level.SEVERE, null, ex);
            throw new RuntimeException("aes getSecretKey error!");
        }
    }

    public static String createKey() {
        //返回生成指定算法密钥生成器的 KeyGenerator 对象
        KeyGenerator kg = null;
        try {
            kg = KeyGenerator.getInstance(KEY_ALGORITHM);
            //AES 要求密钥长度为 256
            kg.init(256, new SecureRandom());
            //生成一个密钥
            SecretKey secretKey = kg.generateKey();
            return Base64.getEncoder().encodeToString(secretKey.getEncoded());
        } catch (Exception ex) {
            Logger.getLogger(AesUtil.class.getName()).log(Level.SEVERE, null, ex);
            throw new RuntimeException("aes getSecretKey error!");
        }
    }

    public static void main(String[] args) throws Exception {
        String s = "hello,您好";
        String password = createKey();
        System.out.println("s:" + s);
        String s1 = AesUtil.encrypt(s, password);
        System.out.println("s1:" + s1);
        System.out.println("s2:"+AesUtil.decrypt(s1, password));

        KeyGenerator kg = KeyGenerator.getInstance(KEY_ALGORITHM);
        //AES 要求密钥长度为 256
        kg.init(256, new SecureRandom(password.getBytes("utf-8")));
        //生成一个密钥
        SecretKey secretKey = kg.generateKey();
        String t = Base64.getEncoder().encodeToString(secretKey.getEncoded());
        System.out.println("tt:" + t);
        // UbNAJLHOTxhNcV5ZFS5ovw==
    }
}
